1. Field of the Invention
The present invention relates to a fitting or instrument for hydraulic flow measurement. The fitting includes a fitting housing containing a principal flow duct, a throttle point arranged in the principal duct, a bypass duct for conducting a partial flow connected behind the throttle point to the principal duct, and a flow measuring device with a movable measuring and indicating member for the partial flow.
2. Description of the Related Art
Fittings of the above-described type can be used for various flow media; they are in use particularly in hot water heating systems in order to indicate the flow of hot water through the various lines of the system. Used for adjusting the flow quantity is an adjustable throttle member, for example, a ball valve or the like, which may be integrated in the fitting housing or may be mounted separately in the line.
In a fitting of the above-described type disclosed in DE-GM 82 20 193.5, a bypass line is flanged outside of the principal housing to two housing connections, wherein the axis of the bypass line extends parallel to the axis of the principal duct. The bypass line includes a window and contains as a measuring length a transparent pipe section through which the partial flow flows. Arranged in the pipe section is a measuring piston which is movable against a helical spring, wherein the measuring piston simultaneously forms the indicating member. A stop valve each is mounted in the two housing connections mentioned above, so that there is no continuous flow through the bypass duct, i.e., in order to limit the contamination of the measuring device by deposits from the flow medium. The manufacture and assembly of this known fitting is very complicated; in particular, various sealing members are required. In addition, for carrying out a correct measurement, both of the stop valves mentioned before have to be open; however, the stop valves are only useful if they are completely closed immediately after the measurement.
Therefore, it is the primary object of the present invention to eliminate the disadvantages of the prior art fittings of the type described above, while maintaining the flow measurement in the auxiliary flow duct. In particular, the operations and expenses of manufacture and assembly of the fitting are to be reduced and the danger of contamination by deposits from the flow medium are to be eliminated.
In accordance with the present invention, the fitting housing includes a side pipe piece forming a side chamber, wherein the side chamber forms the bypass duct and is directly connected to the principal duct in front of and behind the throttle point in the housing interior. The flow measuring device provided with a measuring part and an indicating part is held in the side pipe piece by single hole mounting and closes off the side chamber to the outside, wherein the indicating part is located outside of the side pipe piece and only the measuring part is acted upon by the partial flow.
The present invention makes it possible to significantly simplify the assembly of the fitting because of the single hole mounting of the flow measuring device and because special locking members for separating the bypass duct from the principal duct are not required. In addition, the fitting housing can be constructed with a relatively short structural length at any given nominal diameter. Although the indicating part is in contact with the flow medium, the indicating part is practically completely separated from the flow, so that the readability is maintained without maintenance.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.